The present invention relates to a circuit component and a terminal structure thereof, for use in a wireless communication equipment and the like communication apparatus.
A conventional circuit component and its terminal structure is described in the following using a dielectric filter as an example. FIG. 22 and FIG. 23 show perspective views of a conventional dielectric filter.
Referring to FIG. 23 and FIG. 24, a conventional dielectric filter comprises a coupling board 3 having electrodes formed thereon, a plurality of resonators 5, center conductors 6 and shield covers 7. A circuit board 1 is provided with a grounding pattern and other electrode patterns, which are not shown in the drawing. Also, chip components 2 are mounted on the circuit board 1.
The coupling board 3 is mounted on the circuit board 1 via a spacer 4. The coupling board 3 is provided on the upper and the bottom surfaces with independent electrodes.
A generally-used resonator 5 comprises a dielectric substance provided with a through hole, the surface, including that of the through hole, of the dielectric substance is covered with a conductive layer. Each of the plurality of resonators 5 has a center conductor 6 provided in the through hole, and being coupled with the conductive layer, and the center conductor 6 is connected to respective independent electrodes provided on the coupling board 3. The plurality of resonators 5 are capacity-coupled. The shield cover 7 is attached on the circuit board 1 covering the resonators 5 in the transmittance side and the receiving side, respectively.
The dielectric filter structured as described above is mounted on a circuit board 1 via a spacer 4, and an air gap is provided between the coupling board 3 and the circuit board 1. The air gap reduces a stray capacitance between the coupling board 3 and the circuit board 1. In this way, a change or a dispersion in the characteristics due to a substantial stray capacitance, that could be generated when the coupling board 3 is mounted directly on the circuit board 1, can be suppressed.
In the above-described conventional structure, however, there exists a substantial difference in a coefficient of thermal expansion between the circuit board 1, which is generally made mainly of an epoxy-glass substrate, and the coupling board 3, which is generally made mainly of alumina or the like ceramic material. The difference in the coefficients of thermal expansion creates a substantial stress in a material (a solder, for example) coupling the spacer 4 and the electrode, resulting in micro-cracks or the like problems in the coupling material and causes an electrical connection trouble between the coupling board 3 and the circuit board 1. This is a deteriorating factor in the characteristics.
The spacers 4 of high rigidity were conventionally used, which include a square metal column, a ceramic material covered with a conductive layer, as illustrated in FIG. 25.
A circuit component of the present invention comprises a circuit board (joint circuit board) provided with circuit patterns and terminals for mounting the circuit board on a second circuit board, length of the circuit board being 10 mm-80 mm long. Difference in coefficient of thermal expansion between the circuit board and the second circuit board is 0.2xc3x9710xe2x88x925/xc2x0 C. or more. The terminal is made of an elastic material, and separates the circuit board from the second circuit board for 0.3 mm-5 mm. The terminal comprises a first connection section, a second connection section, and an elastic section disposed between the first and the second connection sections.
At least one of the connection sections of the terminal in an exemplary embodiment of the present invention is provided with a plurality of connection sections, or a connection section is branching out to form a plurality of connection sections. The plurality of branched connection sections is provided at the end with a bent section, or a protrusion.
A structure in accordance with the present invention is advantageous in preventing a possible deterioration in the electrical conduction between the second circuit board and the joint circuit board which would be caused by repeated heat cycles. Thus the present invention offers a circuit component that provides stable operating characteristics for a long operating period.